A New Guy that's gonna need a lot of help

[jtm]

Hi all. I just acquired a pretty good 1987 Comanche. My Jeep is pretty straight, never wrecked, almost no rust. It came factory 4.0 liter in-line six power plant, 4x4 five speed. The first thing to address was an exhaust leak (cracks in the manifold) and a really bad oil leak from the rear main seal. I'm working on those issues but the real head scratcher is the mess of little vacuum lines that run from the tranny up to the engine compartment and then to the front differential. I have some ideas of what's going on but really need to find someone that understands this system and can help me figure out how to proceed.   I'd really appreciate any guidance you can offer. 

[jdog]

What Is your question on the lines, you could also do a cad delete and remove all of the lines

 

@Pete M

or another mod please move to tech questions

[Pete M]

8 minutes ago, jtm said:

Hi all. I just acquired a pretty good 1987 Comanche. My Jeep is pretty straight, never wrecked, almost no rust. It came factory 4.0 liter in-line six power plant, 4x4 five speed. The first thing to address was an exhaust leak (cracks in the manifold) and a really bad oil leak from the rear main seal. I'm working on those issues but the real head scratcher is the mess of little vacuum lines that run from the tranny up to the engine compartment and then to the front differential. I have some ideas of what's going on but really need to find someone that understands this system and can help me figure out how to proceed.   I'd really appreciate any guidance you can offer. 

 

moved to tech for ya.  

 

do check your valve cover first, as leaks at the back can look like an RMS leak.

 

there's a writeup in the link in my signature for bypassing the CAD (central axle disconnect) once and for all and then you can remove most all the lines down there.   

 

 

[cruiser54]

CRUISER'S MOSTLY RENIX TIPS

REAR MAIN SEAL DIAGNOSIS

OCTOBER 31, 2015 SALAD 3 COMMENTS

 

I’d be looking up ABOVE first, and VERIFYING the source of the oil leak YOURSELF.

Everybody, who doesn’t own or have to pay for or perform your vehicle repairs, loves to poke their noggin UNDER the Jeep and come out bearing the false bad news that your RMS is leaking. Many mechanics, friends, and good old Uncle Bob seem to enjoy telling you it’s the rear main seal. Has a catastrophic ring to it, doesn’t it?

A simple leak at the back of the valve cover or other source could produce the same symptoms. You don’t need to be a mechanic to figure this out. If you have good eyesight and a dim flashlight, you’re good to go on your own. Don’t jump on the RMS/oil pan gasket bandwagon right off the bat.

Almost any oil leak on your 4.0 is gonna drip from the RMS area for two simple reasons:

First off, the engine sits nose-up and any oil will run back to the RMS area.

Secondly, the RMS area is also the lowest point on the engine. Simple physics and the old plumber’s adage apply here: “Crap flows downhill”.

Valve cover gasket, oil pressure sending unit, oil filter adapter seals and distributor gasket, in that order, have to be eliminated as possibilities first.  A little tip here. Rather than use a dizzy gasket, use an o ring instead. NAPA #727-2024. Tips 12 and 13 will help you get your distributor back in place correctly. 

 

 

[cruiser54]

Also, with an 87, you should go to www.cruiser54.com and complete Tips 1 through 5 soon. 

[jtm]

Thanks everybody for comments and suggestions. My Comanche had 175 K miles so I decided to replace the engine with a crate unit. The trans and transfer case are in the shop for rebuild. I can do all the swap stuff but need to understand the vacuum shifting of the front hubs. And, I need some advice about what to do with the EGR valve on the intake manifold. My replacement  engine is a 96 HO for a Grand Cherokee. I think everything will bolt up but the 96 exhaust manifold does not have the threaded port for the hard line that comes from the EGR valve. I can TIG in a port for this but would like to eliminate the EGR from the intake if possible.  Any advice ??? 

 On the subject of the front axle hubs; I've heard about what I think is s replacement for the vacuum system. This sounds very attractive to me. If somebody can point me in the right direction I'd surely appreciate it. My apology for my  newness both to the Comanche and to the forum business. I am totally unfamiliar with the terminologies and the way things are done. So please don't hesitate to offer guidance/suggestions no matter how elementary they may be to you seasoned veterans.   Thanks in advance for your patience and help.

[cruiser54]

CRUISER'S MOSTLY RENIX TIPS

HO INTO RENIX SWAP

OCTOBER 31, 2015 SALAD 63 COMMENTS

 

This swap is easier than some will lead you to believe. And generally Pooh-poohed by those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.

• XJ Cherokee and ZJ Grand Cherokee 4.0L engine blocks interchange.
• 2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.
• YJ and 1997-1999 4.0L TJ blocks will interchange in XJ/ZJ
• XJ/ZJ blocks, and the 2000+ TJ/WJ blocks do not interchange without significant modifications.

TJ/WJ 4.0L Engine blocks underwent clean sheet design changes effective in the 1999 WJ Grand and 2000 TJ Wrangler. These blocks are not interchangeable with XJ/ZJ engine blocks. The reason is motor mount bolt holes and belt driven accessory mounting bolt holes are in different locations, or not present at all, TJ/WJ vs. XJ/ZJ.

Now that we know which engines we can use, let’s get down to business.

The HO and Renix have some differences but none that can’t be overcome very easily.

One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from an HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head at the rear for the sender.

You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use a new Renix gasket. Exhaust ports are identical.

An alternative on exhaust manifolds:

As far as exhaust, you can use the Renix exhaust manifold and be fine.
If you want to use the HO exhaust manifold, you must go with an HO headpipe and screw your O2 sensor into that headpipe. Standard Renix harness is plenty long to do so.
A bung can be welded into the HO manifold to accept the EGR tube.

You will need to use your Renix distributor as it is different than the HO design. See Tips #12 – Setting Your 4.0 to #1 TDC and #13 – Distributor Indexing to be sure you get the distributor installed correctly.

The flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.

The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.

As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.

 

XJ: “Regular” (not Grand) Cherokees ’84-’01
ZJ: Grand Cherokee ’93-’98 (Gen1)
WJ: Grand Cherokee ’99-’04 (Gen2)
YJ: Wrangler ’87-’95 (Gen1)
TJ: Wrangler ’97-’06 (Gen2)

10-26-16

[Pete M]

there's no need to retain the CAD and no need for locking hubs.  Jeep eventually did away with both things.  you can do a bypass of the CAD (quick and free, search the link in my signature) or you can remove the shafts and swap in later years' shafts that have bigger Ujoints and a one-piece shaft on the pass side.  

[jtm]

Pete M....Thanks for your help, but I need a little clarification: what is CAD and how do I find links that are "in your signature"?  I'm working to get up to speed with all the abreviations and nicknames you guys use. What is a "Dizzy"?  Thanks again for your patience.

[eaglescout526]

9 minutes ago, jtm said:

What is a "Dizzy"?  

 

Short for distributor. Theres a lot of short names and abbreviations that you will catch on. I think theres even a post dedicated to such.

[jtm]

I guess that makes sense....thanks much. 

[fiatslug87]

In case you have not come across this yet: 

 

[Pete M]

this link: 

 

 

If you're new to MJs, this thread is a great read too:

 

 

[jtm]

Greetings All.   It's been a couple of months since I posted, but I've been busy. Crate motor is installed along with rebuilt gearbox and transfer case. So, all the under truck work is done (for mow). What I'm trying to figure out now is the EGR plumbing. The rigid steel pipe that connects the EGR valve to exhaust pipe. I have a 1987 intake manifold and a 1996 exhaust. I've welded in a bung in the exhaust, but now the original pipe no longer fits. I'm thinking of getting a stainless bellows and welding the threaded end pieces to the ends of the bellows. That will give enough flexibility. But....the bellows is going to be a bit spendy so thought I'd ask you guys for guidance. Can I just eliminate the whole EGR system....block it off and plug the bung?  Is that illegal? Will it mess with the computer?  Any cool ideas about connecting the current setup if I need to keep it.    

[Pete M]

what state are you in?  do they have inspections or sniffers? 

[fiatslug87]

When I put a header on mine the EGR tube would not fit. So what I did was cut the tube and sleeve it with another pipe the correct ID and brazed it in place after attaching both ends for a perfect fit (engine was out of the vehicle). Don't know how far off yours is so this may not work.

Some pictures here: